A few key passages from the last chapter in Theophany: The Neoplatonic Philosophy of Dionysius the Areopagite by Eric D. Perl:
Because being is theophany, all sense perception is an apprehension of symbols of God. In view of this metaphysical basis for his theory of symbols, Dionysius cannot and does not maintain the sharp distinction between intelligible “names” and sensible “symbols.”
…All symbols, in that they are both similar and dissimilar, at once reveal and conceal that which they symbolize, and this is the very nature of a symbol and hence of being as symbol. Not only does a symbol both reveal and conceal, but it does both in one: it conceals precisely in and as revealing, and reveals precisely in and as concealing. Every being, or symbol, is a differentiated expression, a presentation, a coming forth of God into openness, manifestness, availability. As such it reveals God, making him knowable in and as the content of that being. To know anything is to know God as manifest in that thing. The Platonic doctrine of participation, which Dionysius invokes in justifying the suitability of all things as symbols of God, makes it clear that the symbolized is not extrinsic to but present in the symbol, that the symbol is a genuine presentation of the symbolized. But to reveal God in this way is to conceal him. For precisely as differentiated, as finite, and hence as available, as a presentation, every being, or symbol, is not God himself and thus conceals him, leaving him behind, inaccessible, in the dark.
…Only by being concealed in symbols can God be revealed. For if he were not concealed, then what is revealed would be not God but some being, something which is and can be known. If we are truly to know God, if what is revealed is to be God himself, then what we know must be the unknowable, what is revealed must be concealed, for otherwise it would not be God that is known and revealed. Only by symbols is this possible. Hence, as Dionysius here indicates, there can be no non—symbolic knowledge of God, no knowledge of God without the concealment of symbolism. Only a symbol, in that qua symbol it conceals what it reveals, can make God known without objectifying him as a being, enabling us to know God without violating his unknowability, and thus truly to know God. The concealing is the revealing. Dionysius’ doctrine of symbols is thus another expression of the principle that God is given to every mode of cognition, including sense perception, and is inaccessible to all cognition whatsoever.
…It is never true to say, then, that we know God; not from his nature, for this is unknowable and surpasses all reason and intellect; but from the order of all beings, as presented-as-a-screen from him, and having certain images and likenesses of his divine paradigms, we go up, by way and order according to our power, to the beyond all things, in the taking away and transcendence of all things and in the cause of all things. Wherefore both in all things God is known and apart from all things.
…The symbolic nature of being is most fully realized in the angels. …The angels reveal what is hidden; they announce the divine silence; they present-as-screens lights which interpret what is inaccessible. These paradoxes capture the very essence of symbolism: to hide what it reveals by revealing it and to reveal what it hides by hiding it. Any interpretation, in that it is not the meaning itself but an interpretation of it, leaves behind, renders inaccessible, the meaning which it presents. But in view of Dionysius’ understanding of all being as theophany, and the doctrine that the angels possess in an eminent way all the perfections of lesser beings, this is true not only of the angels but, analogously, of all things. To be a being is to be a symbol, to interpret the inaccessible, to announce the divine silence.
…Because of the identity between revealing and concealing in symbolism, there is no opposition between the symbolic knowledge of God in and from beings and the union with God in unknowing by the taking away of all beings. The ascent from sense to intellect to the union above intellect, in which unknowing is the culmination and enfolding of all knowledge, is also the ascent from sensible symbols to intellectual contemplation to unknowing. …In this ascent, the sensible symbols are not merely left behind. For the very nature of a symbol is such that to know it is to unknow it. To understand a symbol as a symbol is to ignore it, to attend not to the symbol as an object in itself but rather to the meaning it concealingly reveals. Conversely, to attend to a symbol as an object in its own right is to fail to know it as a symbol. To a person who cannot read, for example, a written word is an object consisting of ink on paper. But a reader, in the very act of perceiving the word, is oblivious to the word as such and attentive only to its meaning. The more he ignores the word as an object, the more deeply immersed he is in the meaning, the more perfectly he is reading and the better he is knowing the word as what it really is, as a symbol. The non-reader might argue that the reader is simply disregarding the word in favor of something else; this is precisely the attitude of those who see in the Dionysian ascent from sensible symbols to intellectual contemplation to mystical unknowing a rejection or abandonment of sense and symbol. But in fact, of course, it is the reader, who in perceiving the word unknows it in itself, who truly knows and appreciates the word as word.
…The ascent from symbols is the penetration into them. To rise to unknowing, to remove all the veils, to take away all things, is most fully to enter into the symbols, or beings. At the peak, therefore, we find the perfect union of knowing and unknowing, in which all beings are most perfectly known in being wholly unknown just as a word is most perfectly known in being ignored, because all beings are nothing but symbols of God. The mystical union is not a non-symbolic encounter with God as an object other than all things. It is rather a penetration into all things to God who, as “all things in all things and nothing in any,” is at once revealed and concealed by all things. To ascend to unknowing is to see the darkness hidden and revealed by all light, to hear all things “announce the divine silence.”
…The incarnation is thus seen to be fully consonant with, and indeed the fullest expression of, the Neoplatonic philosophical conception of God as not any being but the power of all things, as pure Giving, as Overflow, or, in Dionysius’ terms, as Love. In this sense it is true, as has often been remarked, that Dionysius understands the incarnation in terms of the Neoplatonic metaphysics of procession and reversion. But this need not mean that the incarnation is merely another procession, additional to and parallel with the universal, creative procession of God to all things and all things from God. Rather, Dionysius’ discussions of the incarnation suggest that the whole of being, as theophany, is to be understood in incarnational terms, and that God incarnate, as the “principle and perfection of all hierarchies” is the fullness of reality itself. Being as symbol, as theophany, and hence as being, is perfectly realized in Christ, in God incarnate, the finite being which is God-made-manifest.